This should be possible by setting the CMAKE_PREFIX_PATH variable upon configuring your build. In your project directory generate a test_build directory and run:

mkdir test_build
cd test_build
cmake -DCMAKE_PREFIX_PATH=/home/me/src/opencv/install ..

Setting the CMAKE_PREFIX_PATH variable will make the find_package(OpenCV REQUIRED) command pick your OpenCV installation in /home/me/src/opencv and set the OpenCV_LIBS and OpenCV_INCLUDE_DIR variables accordingly.

Alternatively you can edit a CMakeCache.txt file of an existing build directory with the CMake GUI editor and add the CMAKE_PREFIX_PATH definition there. You have to re-configure your project then.