Create new variable based on partial matching in column R

I am trying to create a new variable in a data.frame based on something like the following data:

df <- structure(list(id = c(123L, 123L, 332L, 332L, 332L, 100L, 100L, 
113L, 113L, 113L, 113L, 551L, 551L), icpc = c("D95", "F85", "A01", 
"A04", "K20", "B10", "A04", "T08", "P28", "D95", "A04", "B12", 
"D95"), icpc2 = c("F15", "", "", "", "", "", "", "", "", "A01", 
"", "A01", ""), reg.date = c("19JUN2015", "15AUG2016", "16MAR2010", 
"20JAN2018", "20FEB2017", "01JUN2017", "11JAN2008", "18MAR2018", 
"19JAN2017", "16JAN2013", "01MAY2009", "03APR2011", "09MAY2015"
)), class = "data.frame", row.names = c(NA, -13L))

I've managed with the following code for the new column condit:

library(data.table)

cond1 <- c("D95", "A01")
setDT(df)[, condit := ifelse(any(icpc %in% cond1 | icpc2 %in% cond1), "yes","no"), by=id]
df

However, I am working with a big dataset (>40 milion) and also want to categorize based on the letter in icpc and icpc2.

My goal is to add a new column which gives yes or no to there being a letter A (so, A01, A04, A50 etc.) in either column icpc or icpc2. I also want all columns with the same id to have yes in the new column condit2.

I was trying the following:

df2 <- setDT(df)[, condit2 := ifelse
                            (any(icpc %in% pmatch("K", df) | icpc2 %in% pmatch("K", df)), "yes","no"), by = PATNR]
head(df2)

This kept on running forever... (I guess, df is too bread anyway, if should have been df$icpc and df$icpc2?)

Than the following to check if pmatch is suitable:

condit2 <- pmatch("K")

And then looked at something totally different:

library(sqldf)
condit2 <- sqldf("df$icpc | df$icpc2, '%K%'")

This should result in the following data frame:

    id  icpc icpc2 reg.date    condit2
 1: 123  D95   F15 19JUN2015    no
 2: 123  F85       15AUG2016    no
 3: 332  A01       16MAR2010    yes
 4: 332  A04       20JAN2018    yes
 5: 332  K20       20FEB2017    yes
 6: 100  B10       01JUN2017    yes
 7: 100  A04       11JAN2008    yes
 8: 113  T08       18MAR2018    yes
 9: 113  P28       19JAN2017    yes
10: 113  D95   A01 16JAN2013    yes
11: 113  A04       01MAY2009    yes
12: 551  B12   A01 03APR2011    yes
13: 551  D95       09MAY2015    yes

Can anyone give a hint? Thanks!!