The simplest method would be to first run a search using the FileLocator Pro user interface with all the appropriate options switched on and then save the search criteria as an SRF file, e.g. DOCSearch.SRF.
You can then use that SRF file from the command line, e.g.
FileLocatorPro.exe DOCSearch.SRF -pc -po -c "Search Text" -o "Results.txt"
The SRF file sets all the valid ZIP, RAR, DOC etc. settings and then you can simply override the search parameters, such as Containing Text.