Filter with ​CONCAT?

A table
name: articles_list
Data provider: {var: read_articles}
Column list:
Beobs.datum:Datum
Beobs.beobachtung:Beobachtung
Article.fundort:Fundort
Author.name:Beobachter
Article.teilnehmer:Teilnehmer
​
I have a filter with a dropdown box
name: field_filter_fundorts
option: {var:read_filter_fundorte}
​
Function:
name: read_filter_fundorte
Fields to retrieve: fundort
​
The filter works with "fundort". The locality is displayed in the drop-down box for selection.
The problem is, I have to see more than "fundort" in the dropdown box.

I've tried using the option in Fields to retrieve:
CONCAT (Beobs.datum, ',', beobachtung, ',', fundort): field_filter_fundorts
Then the filter will not work anymore.

What can I do to make the datum, beobachtung, fundort drop-down box appear, and still the filter on the spreadsheet work?
​
Many Thanx
F.

post update:
​
Where condition:
fundort / LIKE / %{data:field_filter_fundorte}% / Use
Fields to retrieve: fundort
The filter works perfectly.
​
The problem is: In the dropdown field "field_filter_fundorte" also Beobs.datum, Beobs.beobachtung to "fundort" should be displayed.
it does not work with:
CONCAT(Beobs.datum , ', ' , Beobs.beobachtung, ', ', Article.fundort):field_filter_fundorte
CONCAT(Beobs.datum , ', ' , Beobs.beobachtung, ', ', Article.fundort):fundort
fundort:CONCAT(Beobs.datum , ', ' , Beobs.beobachtung, ', ', Article.fundort)
...
​

Array
(
    [log] => Array
        (
            [0] => SELECT `Article`.`fundort` AS `Article.fundort` FROM `mtb_beobachtung_fundort` AS `Article` LEFT JOIN `mtb_beobachtung` AS `Beobs` ON `Article`.`beo_id` = `Beobs`.`beo_id` WHERE `Article`.`user_id` = '909' AND CONCAT(`Beobs`.`datum` , ', ' , Beobs.beobachtung, ', ', Article.fundort) LIKE '%%';
        )

    [var] => Array
        (
            [Pasewalk am Straßenrand, UM] => Pasewalk am Straßenrand, UM
            [Klosterfelde am Waldrand, BAR] => Klosterfelde am Waldrand, BAR
        )

)

CONCAT (model.field , ' - - ' , model.otherfield):model.alias
​
Need spaces surrounding all commas and the alias needs the model name

That would be too easy ... :-)
Actually, it should look like the screen. The date can also be up front.
I have already managed that "date, observation, location" in the drop-down box.
But if I want to filter a dataset then we will see an empty table underneath.
Only if I have the "fundort" in the dropdown box and select a locality, will a result be displayed.
​