From your logic they would be half a human. Seeing as an egg cell is needed as well to actually develop and grow into a human.
Though, seeing as a sperm is a single cell, compared to the billions in a fully grown human. It shouldn't really count for much.
hmm, dunno', don't think semen has any notable aura you could transplant I was more thinking along the lines of the likes of the philosophers stone from FMA for the last panel, but decided against it.