A Cm7(b5,11) respectively Cm11(b5) is a half-diminished chord with additional perfect 4th. Because the 4th is a chord extension (it doesn't replace the 3rd), it is written as 11 in the chord symbol. The 4 only occurs in sus4 chords, where the3rd is adandoned (suspended) for the 4th.
A Cm7(b5) has the notes C (1), Eb (m3), Gb (b5), Bb (7) and F (11). In some chord shapes the 11 is even played instead of the minor 3rd (m3). But because of the characteristc sound of the b5 you will still interpret the chord as m7(11,b5) chord. Hint: the strictly analytically „thinking“ chord analyzer takes it for a sus4(b5) in that case. Syntactically right, but it can’t think like a human being with the words „actually…but…“.
If you abandon the b5 to be able to play the 11 on the guitar, you end up with the same chord shapes that you'd use for a Cm11, where the perfect 5th has been abandoned. Please look up Cm7(11) respectively Cm11 chord shapes without a 5th.
A m7(11,b5) respectively m11(b5) can always be played instead of a plain m7(b5) chord.