Wepener's absence leaves Clermont short of options with fellow hookers Paulo Ti'i and Argentinian Mario Ledesma also struggling with injury.
Clermont directeur sportif Jean-Marc Lhermet has two or three players in his sights as he scours the world for a short-term replacement.
"We've widened our search across both hemispheres," said Lhermet.
"We have two or three potential targets, we're making progress and working hard to get it done quickly."
Clermont diminished the disappointing memories of three successive Top 14 final defeats to be crowned French Champions last season, beating Perpignan 19-6 in the final.
The former Amlin Challenge Cup winners begin the Heineken Cup this year at home to Saracens in a pool that also includes Leinster and Racing Metro.