Finding The Winning Attacking Idea

In the following game, I could only find a draw in a position where a computer discovered that White was completely winning. Would you be able to figure out how to develop the initiative?
Jiganchine, Roman    --    Cao, Jason
BC ch 99th   2014.10.13     1/2-1/2     B92

White to move

38. Qh8+ 
( Instead correct was 38. Rd6+! f6 ( 38. ... Kh7 39. Qf5+ Kg7 40. Qg4 +- ) 39. Qf5 +- Bh4 40. Qf4+ Bg5 41. Qf3     surprisingly White's threats of Rd6-d8-h8 are completely dominating... )
38. ... Kg6 39. Qg8+ Kh6 40. Qh8+ Kg6 41. Qg8+ 1/2-1/2