United have seen Arsenal's England under-21s striker Nketiah and Tottenham Hotspur's England under-20s winger Clarke both recalled by their parent clubs from season-long loans owing to a lack of game time.
Nketiah played his last game for Leeds when making just his second Championship start in the 1-1 draw at West Brom on New Year's Day, after which Whites head coach Bielsa was asked about United's January transfer plans.
Bielsa said the Whites would now analyse the situation but admitted ideally Leeds would land replacements for both players in each position.
Three days on, speaking at Saturday morning's press conference ahead of Monday night's FA Cup clash at Arsenal, Bielsa admitted his side had planned to have Nketiah and Clarke for the whole campaign and that replacements were being targeted, if they could meet the necessary requirements.
Asked first and foremost about replacing Nketiah, Bielsa said: "If we find a player in this position of course we are going to communicate quickly, and if we find one player in this position it's because we are going to consider that it's a good option.
"It’s not about intentions, the question is trying to find the right player and after being able to incorporate him.
"Our sporting director (Victor Orta) always has options and the solutions he proposes always are linked with the solution we are looking for.
"Those solutions are linked with the team profile. But after with those options we have to make arrears and this is not an easy job.
"You have different facts that the club cannot manage. The club doesn't have power in those facts.
"But we know that the club does the right efforts to try to bring options."
Pressed on whether he considered United needed to replace both Clarke and Nketiah - despite Clarke playing only 29 league minutes - Bielsa reasoned: "We planned the season with Clarke and Eddie.
"When we lost them, after we lost them, we would like to replace them. But just if we find a footballer that can replace them.
"We need to another centre-forward and another winger but we need players in those positions that compete with the play of team."