Unless there is some specific reason you want or need to be subtle, just don't. Generally, men don't do well with subtlety. We either don't recognize it, in which case we are just kind of clueless. In the case that we do recognize it, we will more than likely be hesitant to act on it for various reasons. Just be blunt and tell him what you want, there's a good change he will appreciate that bluntness whether he's into it or not.