On a Debian based system the PostreSQL client programs are provided by postgresql-client-common as symbolic links to /usr/share/postgresql-common/pg_wrapper.
If you install that package and attempt to use any of the PostgreSQL client programs like psql, pg_dump, pg_dumpall, and pg_restore, the pg_wrapper without having the version specific binary package installed, like postgresql-client-9.1 it will emit this error:
You must install at least one postgresql-client-< version > package
The easiest way to fix this is to install the postgresql-client metapackage. It always depends on the currently supported database client package for PostgreSQL on Debian based systems and it depends on postgresql-client-common
sudo apt-get install postgresql-client