Term query performance issue with respect to size parameter in search query

This is not needed. Read this and specifically the "Also be patient" part.

I need to know single node how many maximum requests can I process.

It depends... I'd encourage you looking at Rally project to run your benchmarks.

If you have only one node, then that won't help to change the number of replicas. Note that doing a benchmark with one node if you have in production 10 nodes does not make sense to me. You can't extract any valid number from your test.
You should test against a similar platform that you will have in production