Getting off table food?

I recently adopted a little kitty from my grabdparents simply because they found him but don't really want pets. Well they had him for about 2 months and they had been feeding him people food, and now I seem to have a problem with little Marvin climbing into the fridge and climbing onto the dinner table begging for food. He almost refuses to eat his kitty food. So how can I get him to not be addicted to table food? This is my little Marvin by the way :)