Hull's 2-0 home defeat by Aston Villa on Wednesday night means Wolves can make virtually sure of staying up if they defeat Blackburn at Molineux on Saturday.
They are currently six points ahead of the 18th-placed Tigers with three games remaining and also have a vastly superior goal difference.
But McCarthy knows he needs to bring in new blood should Wolves retain their top-flight status and is hoping that would help him to attract new signings.
The former Republic of Ireland boss said: "We'd have to try and improve what we've got (if we stay up). If we don't, then we're just standing still.
"If we stay in the Premier League, then we'll have to try and improve the squad again.
"If you stay up, players (possible signings) might have a bit more faith we can do it again.
"If we stay up, there's maybe the chance of spending more money and bringing better players in.
"The players here are doing great at the minute but it's all about improving the squad."
McCarthy suffered the agony of being relegated with Sunderland and will take nothing for granted until Wolves have ensured they cannot go down.
He said: "I wanted Villa to beat Hull - of course - but if we win our games, then there's nothing anyone else can do about it so let's deal with the situation.
"It would be nice to win on Saturday but we'll keep our feet on the ground."