Newly-single Heidi Klum is wasting no time finding a new man after her relationship with her bodyguard/boyfriend Martin Kristen ended recently. The 40-year-old was caught "making out" with a much younger Vito Schnabel, 27, Saturday night at Hollywood hotspot Bootsy Bellows.

The supermodel mom of four was huddled in a private booth with Demi Moore's ex, going at it hot and heavy, a source inside the club tells X17online exclusively:

    "Heidi was acting like a teenager. I guess being with a younger guy was making her act like she was in high school. She was kissing his face all over as they enjoyed drinks with friends. They hardly left the booth -- they just sat next to each other, touching from the shoulder down, laughing and flirting and making out."

This isn't the first time Vito's gone for an older woman ... he dated Demi Moore for a few months at the end of 2012 -- at the time, he was 26 and she was 50 years old.

Vito's the son of artist/director Julian Schnabel and has established his own name in the art world as a modern art dealer and curator.

The couple left separately from David Arquette's club -- each in their own chauffeured cars. However, inside the club, they were anything but separate; our source tells us:

    "This looks like a hot romance. I don't know if it's going to last, but there is some serious chemistry between these two. They were both totally into each other."