Blues recently completed the signing of teenager Ravel Morrison on a season-long loan from West Ham.
Clark refused to name any of his possible targets but admitted there were more players on the way.
"Before the end of the week I'm hoping to do a bit more business," he told the Birmingham Mail.
"And then I think I'd be done, unless we have to go into the market to replace anyone who goes out of the club."
Norwich striker James Vaughan has been linked with a move to the Championship side, along with Chelsea defender Ben Gordon.
Clark, however, played down talk of a move for the former Everton starlet.
He added: "We've got four [senior] strikers at the moment and I can't see how five would fit into the equation. You always look for four, and that's where we are."
