It depends on the aim of serum starvation- if aim is to induce autophagy, no serum will be desirable. If growth arrest, 0.1% serum would do. Therefore, share your aim and it should be possible to suggest.
Starvation usually mean complete removal of FBS. Also consider the inputs of Dr Choubey. It may be interesting to vary concentration with aim of experiment.
Just as Dr Choubey mentioned, it depends on the aim of your study. If you are interested in investigating certain proteins in the secretome of HeLa cells, then you should not add any FBS to your DMEM.