Preflop
A5s is the perfect 3-bet
bluffing hand, so as others have said, if I was going to play this, I would just jam preflop. It is a little bit borderline though with so many blinds and 4 players left to act behind. So if the Villain is tight or dont fold to 3-bets, I might just fold this. I dont like calling, because you are putting in 10% of your stack basically just hoping, that nobody behind will 3-bet, AND that you will smash the board.
Flop
I lean towards checking here, because you have some showdown value with bottom pair. Also with a flushdraw there is less value in folding out random overcards, since some of the outs, that might give them a pair will also give you a flush. As someone else have said, a check-jam is a pretty sexy option here, and if you are going to bet, then half pot is enough. When you pot it, you are essentially telling everyone, you are never going to fold, which takes away their ability to
bluff.
Turn
As played you have kind of painted yourself into a corner, since so much of your stack is committed already, that you can not really fold, even though you are usually behind.
Results
Him showing up with top set is pretty much the worst case scenario, and you brick. Given his holding there was no way to avoid going broke, once you decided to call pre.