Hillary Clinton is grabbing every celeb she can find so she can match Bernie Sanders in financial firepower.  

Clinton had a huge fundraiser Wednesday night at Radio City Music Hall. Among the stars, Katy Perry, Elton John -- both of whom performed -- Neil Patrick Harris, Jamie Foxx, Julianne Moore and Orlando Bloom.

Clinton, who's ahead by a mile, fell $10 mil behind Bernie in fundraising last month.