You can use zipgrep on Linux or OSX:
zipgrep "BEGIN REQUEST" file.jar
If you wish to search a number of jars, do
find libdir -name "*.jar" -exec zipgrep "BEGIN REQUEST" '{}' ;
where libdir
is a directory containing all jars. The command will recursively search subdirectories too.
For windows, you can download cygwin and install zipgrep under it: http://www.cygwin.com/
Edit 1
To view the name of the file that the expression was found you could do,
find libdir -name "*.jar" | xargs -I{} sh -c 'echo searching in "{}"; zipgrep "BEGIN REQUEST" {}'
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