Total Commander

I'd like to be able to search for files that contain multiple phrases.
Like 'dog' and 'biscuit' but they might not occur exactly as "dog biscuit"
The file might contain "I feed my dog biscuits as a reward"
Most people don't know/understand Regular Expressions.

I'm suggesting that TC should behave the same way a search engine does.
Most people are familiar with google's syntax, so that would be suitable.
There should be a new Checkbox, 'Exact Phrase' which is ticked by default; you can untick it (and it will save its unticked state) and then it will behave like a search engine.

So you can do searches like
term1 term2 -term3
(dog|cat) biscuits
"I feed my (dog|cat) * as a reward"

Don't support. Many people that familiar with TC and other file managers for many years expect actual behaviour and not Windows one.

(dog|cat) biscuits
Regex: (dog|cat).*biscuits

"I feed my (dog|cat) * as a reward"
Regex: I feed my (dog|cat) .* as a reward
or more accurately, use word boundary:
Regex: I feed my (dog|cat) \b.*\b as a reward
or, allow plural dogs|cats ...
Regex: I feed my (dog|cat)s? \b.*\b as a reward

Not that different from the watered down syntax that search engines allow us to use. Not only that but google used to actually search what you typed in quotes as an exact string -- it no longer does so. It will allow different spellings, plurals and all number of things.
To actually get the search results from google or other engines now, you need to do an excessive number of -excludes to even try to override it's inane logic.

You'd be much better off trying to learn something new -- as I doubt this request will meet much support from other users or the author

Interesting.
I reckon they call it RegEx because you need to use it regularly to be able to use it

I had the same idea (google like search) and wrote the plugin: QuickSearch eXtended

You may use it with TCs Quickfilter feature.
If you want to search for files in subdirectories you could switch to branch view before using Quickfilter.