Pat Metheny is pretty much everywhere. For the past four decades, the 70-year-old guitarist has been crisscrossing the globe, playing an average of 150 shows a year. Instantly recognisable thanks to his wild mop of hair and the custom three-necked, 42-string guitar he wields on stage, Metheny has released more than 50 albums, won 20 Grammys and collaborated with David Bowie and Joni Mitchell, as well as free jazz pioneer Ornette Coleman and bass legend Jaco Pastorius. When we speak, he is 160 dates into a solo tour and fighting with patchy wifi in a hotel in Nancy, France, that aptly leaves an image of a guitar with hundreds of strings on screen rather than his signature plumage.

While he meticulously keeps written records of each show to improve on his performance, Metheny is widely considered a master improviser and virtuoso, pioneering an intricate, harmonic style that is as dextrous as it is melodic. Between shows and travel as his current tour kicked off, Metheny recorded 13 solo compositions that make up his latest release, MoonDial. Spanning the intimacy of Chick Corea cover You're Everything to a downtempo reworking of his 2012 composition This Belongs to You and the instantly recognisable melody of the Beatles' Here, There and Everywhere, it feels like Metheny at his most tenderly introspective.

Growing up near Kansas City with a trumpet-playing father, Metheny took up the horn as his first instrument. It was a Beatles TV performance that would turn his attention to the guitar. "The word was I was a terrible trumpet player and so I was keen to move on," he laughs. "I got a guitar for my 12th birthday and played it non-stop in high school. But the ability to think in trumpet stays with me; I always take a breath before I play a note. That moment of pause really helps me."

By 18 he had developed a reputation as a prodigy and was offered a place at the University of Miami. "It was the happiest day of my parents' lives because I hadn't taken a book home since I was 14, so they had resigned themselves to me never getting into college," he says. "The second night after I arrived in Miami, I went to a jazz club. This guy played bass for one tune and it was like he had dropped out of a spaceship. That was the first time I met Jaco Pastorius" - who would go on to be one of the most influential bassists of all time.

The pair struck up a close friendship and began playing together "on a series of dumb gigs with D-list celebrities in Miami Beach," he laughs. Within a year, the university hired Metheny to become a faculty member. By the time he turned 19, Berklee College of Music poached him to teach at their faculty. "It was a crazy time, since neither me nor Jaco had any notoriety, we were just playing," he says. "Not long afterwards, Jaco joined [pioneering fusion group] Weather Report, released his debut album and I put out my debut. That all happened within a few months."

Following the release of that album, Bright Size Life, and the heralding of Metheny's sinuous guitar style as a bracing new voice in jazz, the relentless touring began and Pastorius started using drugs. In 1979, though, he and Metheny had the opportunity to play with Joni Mitchell on her Shadows and Light tour. "I always try to get into places where I'm not quite sure what to do and playing with Joni was one of those," he says. "But Jaco was a different Jaco at that point and I thought by doing that tour I might be able to help him." Pastorius died in 1987 after an altercation with a nightclub employee.

While Metheny may have been surrounded by musicians with substance issues, he himself has never had a drink, tried drugs or smoked. "It's not for a moral reason, I've just never been interested," he says. "I can look at the table in front of me for like an hour and think: 'Wow, somebody made that,' so I'm tripping out all the time already. I can't even imagine what would happen with substances involved."

Someone who might have matched Metheny's capacity for tripping out at the miraculousness of everyday life was David Bowie, with whom he worked on the score for the 1985 film The Falcon and the Snowman. "He's one of the most amazing presences I've ever encountered," Metheny says. "We first met to watch a cut of the film together and he was busy scribbling on a yellow legal pad, which by the end had 25 or 30 of the most brilliant song ideas on it. When we then went to record the track, it was like watching a master at work: he did the whole thing in two takes and we watched him on a video feed from the vocal booth. I had to keep telling myself it was real rather than television."

But for someone with such a rich history of encounters and collaborations, there is only one thing Metheny is relentlessly focused on: moving forwards. "I've got no interest in looking back, since doing something well before has no impact on what might happen tomorrow," he says. "I'm lucky that I'm still fit enough to play 160 or more dates a year and I will keep going as long as I can. My existence is all about what's next." And with that, Metheny has another show and another audience to prepare for.