Hey S.! I think just about every mom has experienced feeding issues like this, so you're not alone :-) I suggest you work on hand control during meals. Train him to keep his hands in his lap during meals while you feed him the correct way. Demonstrate, while his hands are folded in his lap, how to use a spoon, how the food stays on the plate, etc. Then slowly give him freedom to hold the spoon/fork, use it to get food off of his plate, and finally to put the food in his mouth. Once he has mastered the art of using utensils, refuse to let him eat any other way. He will quickly learn that when he's hungry he must eat using proper table manners.
As with all training, it can be painful and tedious. However, if you stick to your guns, he will come around to your way. On a side note, teaching hand control at an early age has many benefits. It minimizes the need for correction for touching issues while shopping, at Grandma's house, in doctor's offices, etc. We taught self control to our children and it was such a blessing to us and those around us! Best wishes!
Warmly - J.