Fold flop. Pokerstove your equity vs even a very aggro range for the opponent and I'll be shocked if you have greater than 35% equity. Add to the fact that 44 on K86, even with a spade, will have a terribly hard time realizing what little equity it has.

The turn is extremely bad. You're just in such bad shape when he's not bluffing, and even when he's bluffing he'll often have 14 outs. I like your bet, not for protection but to bluff and with the intention of bluffing the river if he check calls. It's not a protection or value bet though, although it might have a small element of that in it's EV.