I use Agent Ransack by MythicSoft, a free download that lets you search for content words/phrases, file type, date range, title, etc.:
https://download.cnet.com/agent-ransack/3000-2072_4-10043846.html
Yes, that is the best IMO. Searches inside files, including ODT. And Agent Ransack 2016 (for Win 7 or higher) can be downloaded from here: Agent Ransack 2016 32/64 bit
Noted!