Pokerstars 1.20 45 Final three

[Highn]

I was kind of confused playing this hand, and I feel I can greatly improve my game here. The button has been pushing lots of hands (and just lost a huge pot to SB, who called his pre-flop all-in with K5). Would appreciate your insight, thanks in advance.

PokerStars No-Limit Hold'em Tourney, Big Blind is t800 (3 handed) internettexasholdem.com

Hero (t21710)
Button (t6438)
SB (t39352)

Preflop: Hero is BB with 7[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/heart.gif[/img].
<font color="#CC3333">Button raises to t6388</font>, SB calls t5988, <font color="#CC3333"> Hero ?