C#: what's the equivalent of SQL "LIKE" feature?

My example code:

public static bool StringSearchHit(string keyWord, params string[] targetArray)
{
    foreach (string targetItem in targetArray)
    {
        if (targetItem.IndexOf(keyWord, StringComparison.InvariantCultureIgnoreCase) >= 0)
            return true;
    }
    return false;
}

The problem I have: the LIKE operator in SQL is not just string.Contain() or string.IndexOf(), there are "culture character similarity" in it (I don't know how to call it).

Example: when I search using LIKE '%pokemon%', the "Pokémon" will also be included. The character "é" will be considered as similar to "e".

Same for some German characters. The special characters "ä ö ü" will also be considered "like" "a o u" in SQL.

My goal: when the keyWord is "aou", and one of the targetArray has "äöü", it will also return true.

Is there any equivalent of this in c#?

Edit: thanks for pointing out about another post:

Ignoring accented letters in string comparison

That is the correct direction, but in another issue, it's "compare", not "contain". How to do similar thing in "string.Contain"?

Edit 2: Thanks for the correct answer:

Complex "Contains" string comparison

Tried this solution, "Pokémon" can be searched using "Pokemon", and "Æon Flux" can be searched using "aeon".

Case close and marked as duplicate.