lpatch is a patcher, in short a program which performs some instrcutions (those contained in lpatch.dat or the various *.lpatch files) on a file.
So you must use the right .lpatch file with it otherwise it does nothing.
For example if you want to apply the q3infofix patch you must download the lpatch program and the q3infofix.lpatch file.
Video:
http://mirror.aluigi.org/video/lpatch.avi