Barca play CONCACAF champions Atlante of Mexico in the last four of the competition in Abu Dhabi on Wednesday and a triumph in the final against Estudiantes or Pohang Steelers would give them their sixth trophy of a remarkable 2009.
"To be considered a great club you have to have won the World Club Cup," Begiristain said on Barca's website.
"We have tried not to obsess about our desire to win this title but the reality is that it would please us a lot because it's the one Barca is missing."
Begiristain was involved as a player when Barca made their first unsuccessful attempt to win the world club championship following their European Cup victory in 1992 and was technical director when the Catalans failed again in 2006.
In coach Pep Guardiola's first term in charge last season, Barca won La Liga, the European Champions League and the King's Cup and have since added the Spanish and European Super Cups.
"Everyone knows the significance of winning the Club World Cup, the players above all," Begiristain said. "They want to round off their careers with this title."
The first semi-final is on Tuesday between Asian champions Pohang Steelers of South Korea and Argentina's Estudiantes.
