The Blues boss has also insisted that he will hand opportunities to the team's younger players in the new campaign.
"How many more players? It's a tough one because as you know and as I've shown in the past, I like to promote from within as well," Clark told the Birmingham Mail.
"The scholars came in on Wednesday and I've sat down with them to throw down the gauntlet - why not you take the positions or have a go at taking the roles? There's that possibility, but there's also a possibility in regards Shane Ferguson and Ravel Morrison.
"We're still in dialogue with Newcastle United and West Ham United. I would really like to get them, but we've got to see."
Morrison and Ferguson spent last season on loan from West Ham United and Newcastle United respectively.