[Gammix]

Use this anywhere to show a search dialog:

pawn Code:

ShowPlayerDialog(playerid, DIALOG_ID_HERE, DIALOG_STYLE_INPUT, "Search Dialog:", "The content here!", "Search", "Cancel");

Now, for functionality of the dialog, use this:

pawn Code:

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[])
{
    if(dialogid == DIALOG_ID_HERE)
    {
        if(response)
        {
            if(! strcmp(inputtext, "example text"))
            {
                //if you want the inputext match with the specified text completely!
            }
            
            if(! strfind(inputtext, "example text"))
            {
                //if you want the inputtext be relative to the specified text!
            }
        }
    }
    return 1;
}

According to your words, this is what i think you want.