Currently only the development-branch builds against OF 4.0. Also you need to apply a patch because of a bug in OF4.0 (and also v1606+. Which you probably mean. I'm not aware of a v1616+). I quote from the README

Support for OpenFOAM v1606+
This version is supported in the this version of
=swak4Foam=. There is only one problem: there were changes to the
=tmp=-template. These changes have been taken care of in the
=swak4Foam=-sources.
But there are two source files in the
distro that need to be modified (basically adding =.ref()=
instead of =()= in three places:
: src/finiteVolume/finiteVolume/fvc/fvcD2dt2.C
: src/finiteVolume/fvMatrices/fvMatrix/fvMatrixSolve.C
Therefor the officially released version will
never* compile
with =swak4Foam= but this is nothing that can be fixed in
=swak4Foam= (the patch is found in the directory
=distroPatches/OpenFOAM-v1606+=)
Support for OpenFOAM 4.0
This version is supported in this version of =swak4Foam=. There is
one problem: the released version has two problems that mean that
=swak4foam= will
never* compile on the released version.

 Patches fixing these issues are found in the directory
 =distroPatches/OpenFOAM-4.0=