What do you mean by Super-hero game, though?
All DnD PCs have superhuman abilities and resistances, especially at high-level, so I would say that DnD is by default a "super-hero" game.
Clearly, all these powers come from "magic" in DnD, but then it is a simple matter to reskin the spells and class features as superpowers.
For a Constantine/Batman kind of game, you could probably use DnD as it is.
To reach Superman levels, I guess you could integrate magic items as "powers". After all, how may times did your PC lose all his equipment?
Imagine Superman as a lvl 20 sun soul monk with a Belt of Giant Strength, and Boots of Flying. Laser-eyes, super-strength, flight, the bases are covered.