Have you installed both
the fftw and fftw-devel packages? Check where the include files and libraries have been installed:
$ rpm -ql fftw-devel | grep include
$ rpm -ql fftw-devel | grep lib
then try to specify the correct path using the environment variable LDFLAGS and CPPFLAGS as suggested. For example:
$ export LDFLAGS='-L/usr/lib'
$ export CPPFLAGS='-I/usr/include'
You don't really need to export these variables if the include files...