How big is your turtle/approx how old is he?
For turtles under a year old, they should be fed a "head sized" amount every day. This is the amount of food that would fit in the head (NOT including neck) if it were hollow.
Adults can be fed a head sized amount every second day. If you want to feed him every day, you can feed him half a head size every day.
It could be that he's set in his ways because he knows that you're sure to give him the yummy meats if he refuses everything else
If he's healthy, you should try the "tough love" approach. Give him nothing but pellets/veggies for a week, and with luck he'll be hungry enough to try the staple food.
Too much meat = too much protein, which can cause pyramiding (shell problems), which then can lead to organ problems as well.