I am facing couple of challenges with Dynamic SOSL.
Records are available with "test.abc1@test.digital or test.abc@test.com" and "(123) 456-7890"(based on locale).

we are using Dynamic SOSL query with multiple search terms and asterisk match (*)

Email field not working with :-

1)searchTerm ="@test.digital*"
2)searchTerm ="abc1*"
3)searchTerm ="abc1@test.digital*" or searchTerm =".abc1@test.digital*"

Phone number not working with :-

1)searchTerm ="890*"
2)searchTerm ="23)4*"
3)searchTerm ="67890*"

***We ant fetch records with any character from email field and any number from Phone number field.*** 

we tried multiple ways suggested by salesforce i.e. 
https://developer.salesforce.com/docs/atlas.en-us.soql_sosl.meta/soql_sosl/sforce_api_calls_sosl_find.htm

Code :-
SearchCaseByMultipleId(string searchText){
        String searchTerms = '(';
        for(string str : searchText.split(',')){
            if(str.length()>0){
               searchTerms  = searchTerms+' "' +str +'*'+'" '+'OR';
            }else{                
            }           
        }
        searchTerms = searchTerms.removeEnd('OR');
        searchTerms = searchTerms+')';
       string finalQuery = 'FIND :searchTerms IN ALL FIELDS RETURNING '+objectName+'(' + quryFields +' 
         ORDER BY CreatedDate DESC NULLS last)';
       list<list<Sobject>> results = search.query(finalQuery);
}
search term looks like :- ("@test.digital*" OR "abc1*").

is there any other way for my requirement or is something missing?