I have a son about the same age and we have also experienced fussy eating. My son is extremely picky with vegetables, but he will still eat baby food veggies, so that's what he gets everyday. I mix up a jar of green veggies with a jar of orange veggies everyday for lunch and the crazy kid actually likes it. Go figure! I don't care if people think it's weird at his age to still be eating baby food - if that's the only way he'll eat vegetables, then that's fine by me. The important thing is he's that he's eating them one way or the other, and I know he'll eventually learn to like eating regular veggies.
I will also sometimes mush up regular veggies and mix it in with his baby food veggies - like cooked brocolli, carrots, sweet potatoes, etc. I've also mushed up some cooked brocolli - so it's almost like a paste - and put it in the middle of a grilled cheese sandwich and that's worked well. If your son eats spaghetti or lasagna, try mushing up some vegetables and mixing it in with his marinara sauce. Oh, and another trick I've used is giving him a "dipping sauce" for his veggies or meats. I've tried a mild bbq sauce, ranch dressing, and ketchup (which is his new favorite). It makes eating more fun for him since he can dip his own food (and yes make a mess sometimes.)
For fruit, try mixing up some fresh fruit in a blender with some whole milk, yogurt, and a little OJ to make a smoothie. He may think it's cool to get such a special "treat" and if he drinks it, it's a great way for him to get a good dose of fruits, calcium, and protein all at once.
As far as meats, my son loves chicken nuggets and hot dogs. I buy the organic kind that have no nitrates and are low in sodium so I don't feel bad about him eating those kinds of foods all the time. You can also find frozen deli meat that is minimally processed with no nitrates as well - Applegate Farms is the brand I get.
For snacks, you can find crackers and other snack-type items in the baby food aisle at the grocery store that are specifically made for toddlers...like veggie crackers, freeze dried fruit bits, etc. They are lower in sodium and cholesterol than other snacks, and my son absolutely loves them.
Good luck!