By default, Windows 7 index service will not go into LibreOffice files to search their contents. This can be enabled by installing a plugin at IFilterShop and the download link for non-commercial users is here. After installing this plugin, we still need some configuration in Windows according to the "Windows Desktop Search" part in the online readme.

When integrated with Windows Desktop Search, OpenOffice IFilter uses temporary directory to process StarOffice/OpenOffice files. By default it uses system temporary directory. For Window Desktop Search versions 3.x and higher OpenOffice IFilter must be set to work with user specified temporary directory. To change temporary directory setting:

1. Stop Windows Search service.
2. Open registry key "HKEY_LOCAL_MACHINE\SOFTWARE\IFilterShop\SOFilter"
3. Add new String value named "TempPath" and enter the full path to the new temporary directory. If this value is missing, empty or the path is not pointing to a valid directory, system temporary directory will be used. Please make sure that "Users" or "Authenticated Users" Group has "Full Control" permissions to the custom temporary directory.
4. Start Windows Search service.

When using custom temporary directory, we recommend that you set it as "not indexable" in all your indexing products. Otherwise temporary files may be indexed. This will pollute the index and also can prevent temporary files from proper removal by OpenOffice IFilter.

Next, we should go to "Control panel", search for "Indexing options" and the following dialog comes out:

By clicking "modify", we can select which folders are to be included in the index.

And in "Advanced" dialog, we can search which file types can be searched and whether or not their contents will be indexed. Therefore, just add those file extensions of various LibreOffice files and select "Index Properties and File Contents".

Finally, rebuild the index in "Advanced options".

After a while, we can search into the LibreOffice documents.