B767 First Officer reported a Spoilers EICAS message during climb. The flight returned to the departure airport and landed overweight.

Narrative

During climbout from ZZZ enroute to ZZZZ; the PF was having difficulty keeping the aircraft tracking straight. The Relief Pilot noted the PF was requiring large inputs to keep the wings level. While cleaning up the flaps; we noted the 'Spoilers' EICAS message. While PF continued flying; the Relief Pilot and I referenced the abnormal checklist. After leveling at 12;000' and assigned a speed of 270 kts; the PF engaged the autopilot (AP). There was a noticeable 'bump' and the aircraft seemed more controllable. The PF disengaged the AP and noted that the aircraft still required some control deflection. After reviewing the status page to see the amount of control deflection required for wings level flight; the Capt asked the Relief Pilot visually confirm the control positions. The Relief Pilot went to the back and reported that the 2 inboard spoilers on the right wing appeared deflected upward beyond other control surfaces. Upon leveling at 17;000' the PF tried re-engaging the AP. Despite being in HEADING mode and with the heading bug centered on our current heading; the aircraft immediately began turning right. The AP was disengaged and we determined it would be best to continue hand flying. Discussing our situation as a crew; we felt there was a definite question as to the status of the flight control system...we concluded the best and safest course of action was to request priority handling with ATC and return to ZZZ. We accomplished a briefing for the ILS XXR at ZZZ; accomplished the Descent and Before Landing checklists; consulted landing distance for the wet runway; and reviewed overweight landing procedures. The PF accomplished a hand flown ILS to a normal touchdown.