It looks like chef-client and other binaries have been moved to chef-bin ruby gem. I could not find that in the package list.
A separate question is whether it should be separate or included in this port.
I guess it is how it is from the upstream.
-- Output ---
# tar tJf rubygem-chef-13.8.3_2.txz | grep bin/chef-client
# tar tJf rubygem-chef-15.14.0.txz | grep bin/chef-client
Upstream moved the binstubs to chef-bin gem.
I've added sysutils/rubygem-chef-bin in r561119.
One thing I'd check is if it asks for a licence. When directly installed it asks for the Chef licence to be accepted. I'm still puzzled how that is being distributed by the upstream as an apache 2.0 licenced, but it asks for a different licence to actually use it.