Comparative clause

"We distinguish three main classes of finite subordinate clauses:
I couldn’t find the book that I wanted (relative)
He gave me more copies that I wanted (comparative)
You know that I wanted it (content)
Content clauses can be regarded as the default category of this dimention: they lack the special properties of relative and comparative clauses, and their structure is less different from the main clauses. (…)
The term content clauses reflects this default status: it suggests that the clause is simply selected for its syntactic content. (Huddleston&Pullum, 2005, p 950)."

Should there be "that" in the comparative clause "He gave me more copies that I wanted"?