No-Limit Hold'em, $1.00 BB (5 handed) - Hold'em Manager Converter Tool from FlopTurnRiver.com

Button ($207.10)
Hero (SB) ($107)
BB ($170.25)
UTG ($101.35)
MP ($64.25)

Preflop: Hero is SB with 6, 7
1 fold, MP calls $1, Button calls $1, Hero calls $0.50, BB checks

Flop: ($4) 5, 4, 3 (4 players)
Hero bets $4, 2 folds, Button calls $4

Turn: ($12) 9 (2 players)
Hero bets $10, Button calls $10

River: ($32) 10 (2 players)
Hero checks, Button bets $16, Hero ???

The ony reads I had on villain was that he was playing a LAG game.
villain's 1/2 PSB bet on river can be either for value or as a bluff, however, with what hands would he call flop/turn on a flush board? Maybe 1 pair + heart, overpair with one heart, Ah or Kh? Maybe 2 pairs?
Standard fold?