Wiktionary
multisexual
a. 1 Of, or pertaining to, more than one sex. 2 (lb en neologism) sexually attracted to more than one genders.
Usage examples of "multisexual".
And he was having an affair with a multisexual chief engineer, who was in turn (according to the latest rumors, and since the entire vessel seemed to be powered not by dilithium crystals but by innuendo, it was probably accurate) serving to sate the mating lust of the normally staid chief medical officer.