I can confirm that neither Debian 7 + LXDE using v18.104.22.168 or Crunchbang 11 + Openbox using v22.214.171.124 (both website versions) offer wildcard support for the File Open dialog. The File name field only appears when the Tools > Options… > LibreOffice > General > Open/Save-dialogs section > “Use Libreoffice dialogs” option is checked. Regardless of whether the full path and wildcarded filename or just the filename is entered, the displayed list of files is unaffected.
Bugs fdo#46221 and fdo#61557 are related to getting this dialog simplified / cleaned-up however there is no report that I can find relating to wildcard support. Do you know in which prior version it was working?
EDIT: I have also tested Crunchbang 11 + Openbox using v126.96.36.199 (website version) and again there does not appear to be any wildcard support for this dialog. It is possible the help page information is Windows-specific, and that it is the documentation that requires amending.