The pair both made their Blues debuts off the bench in the second half of Saturday's 1-1 draw at home to Blackpool.
Poland international midfielder Dudka has been building up his match fitness ever since arriving as a free agent on a short-term deal at the end of October, while striker Mclean, on loan from Hull, only made the switch to St Andrew's ahead of the clash against the Seasiders.
And Clark feels they will both grow with Birmingham in time, with the duo initially due to remain at the Championship club until January 1.
"I think they showed little flashes. They'll be better for it," Clark told the club's official website after their debuts.
"Dariusz needs a bit of time in terms of fitness levels but I think we've seen some of the quality he has on the ball. It's a completely new game to him in English football, the tempo and speed of how the game's played, so he needs to get used to that.
"Aaron only came on Friday and he's met the lads for a 45-minute session. As he gets to know us better and we get to know him better, it'll be easier for us."