How do you tell someone to stop being so clingy?

i've been dating someone for about a month and a half. i knew him for about three months before we started going out. lately in public we're always holding hands and kissing and i feel like it's a little too much PDA, and it's making our friends and family feel uncomfortable. he's incredibly sweet and puppy-ish though, so how can i break it to him that he needs to stop being quite so clingy without hurting his feelings and making him stop altogether? thanks.