At that point, it's most likely a fold, but you've already committed a lot of money to the pot...if may have been worth the call. The early action indicates that he

There are a lot of possibilities here...the fact that he reraised you big on the flop either meant that he had 2pr, trips, a king with a decent kicker or was stealing the pot. If you're going to committ yourself to a pot like that by calling his reraised on the flop, you may as well just go ahead and get all of your money in on the flop.

Then, he checked the turn in front of you, which likely means he was afraid that you caught a flush or trip 6s. You may have been able to bet there and take down the pot.

By the river, it's too late. He only needs one of 11 card to beat you(a 6 or a heart).

But to make any real determination, we'd need some info on that guy...