Equals and Contains for text search
The flow control seems excessively verbose.  This would do the same:

public override bool PropertySearch(string value, bool searchPartial = false)
{
    return searchPartial ? (dataValue.IndexOf(value, StringComparison.OrdinalIgnoreCase) &gt;= 0)
                         :  dataValue.Equals(value, StringComparison.OrdinalIgnoreCase);
}


I would also question your decision to lump these two operations together into the same method.  The code would likely be clearer if you wrote two separate methods.  But you haven't shown the superclass or rest of this class, so I can't say for sure.